POLY(ARYL ETHER KETONE) BLOCK AND CHAIN-EXTENDED COPOLYMERS .3. PREPARATION AND CHARACTERIZATION OF POLY(ETHER KETONE KETONE) POLY(ETHER SULFONE) BLOCK COPOLYMERS

Poly(ether ketone ketone)/poly(ether sulfone) (PEKK/PES) block copolymers have been prepared by the nucleophilic polycondensation of difluoro-terminated PEKK oligomers with 4,4-bisphenol-S and 4,4'-difluorodiphenyl sulfone. The condensations were conducted in diphenyl sulfone at 300-degrees-C with base/promoter systems such as sodium carbonate/potassium fluoride or calcium carbonate/potassium acetate. Mechanical properties were similar to those of PES, with tensile strength and modulus increasing at higher PEKK levels (near 80 wt %); materials comprising these high PEKK levels were crystalline as molded with melting points >300-degrees-C. At 65 wt % PEKK, crystallinity could only be induced by annealing. The polymers had a single T(g) which decreased as the PEKK content increased. Stress-crack resistance of the copolymers improved to ketone-containing solvents, improved modestly to aromatic solvents, and did not improve to chlorinated aromatics.